Question

Read the assertion and reason carefully to mark the correct option out of the options given below.

Assertion: When a tiny circular obstacle is placed in the path of light from some distance, a bright spot is seen at the center of shadow of the obstacle.

Reason: Destructive interference occurs at the center of the shadow.

A. Both assertion and reason are true, and the reason is the correct explanation of the assertion.
B. Both assertion and reason are true, but reason is not the correct explanation of the assertion.
C. Assertion is true, but reason is false.
D. Assertion and reason both are false.

Answer 1

The bright spot seen at the center of a shadow cast by a circular obstacle is due to constructive interference, not destructive interference as the reason incorrectly suggests.

Step-by-step explanation:

The student's question involves understanding the phenomena of light diffraction and interference patterns, specifically related to the appearance of a bright spot at the center of a shadow when a small circular obstacle is placed in the path of light. The assertion states that a bright spot is observed, which is correct. This is known as Poisson's spot or the Arago spot, and it occurs due to constructive interference of the diffracted waves at the center. The reason given in the question is incorrect, as the bright spot at the center is not due to destructive interference, but rather due to constructive interference. Therefore, the correct answer is:

C. Assertion is true, but reason is false.